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Very small SAW filters of the size 0.8 mm x 0.6 mm based on wafer-level packaging technology are fabricated and tested. Excellent electrical performance as well as robustness against humidity and mechanical stress are demonstrated. Complete devices are fabricated on a wafer, instead of bonding with a ceramic substrate or another wafer. A structure with a hollow space is built on the piezoelectric substrate by semiconductor processes in order to allow the surface acoustic waves to freely propagate without any loss. Either LGA or BGA type of terminals are available with the filter. It is demonstrated that the developed WLP SAW filters are suitable for use in high-performance RF front-end modules.